Not Applicable
Not Applicable
The present invention relates to an electrically and mechanically redundant release mechanism for release of an element and, more specifically, to such a release mechanism which is useful for actuating non-explosive, frangible actuator devices for quick release of loads coupled to such devices. As such, the present invention is an improvement and variation of application Ser. No. 09/498,761 filed Feb. 02, 2000 entitled xe2x80x9cFrangible Actuator with Redundant Power Supplyxe2x80x9d and assigned to the assignee hereof. Ser. No. 09/498,761 is incorporated herein as if set forth in haec verba.
While the present invention was devised for specific use with non-explosive, frangible actuator devices for quick release of loads coupled thereto, it is to be understood that the present invention has broader applicability and, therefore, it is not intended that it be limited thereto. However, because of this expressed use, the following exposition will be specific to such frangible actuator devices.
Accordingly, non-explosive frangible actuators are used to perform a task, often releasing a tensile load (such as a stowed solar array or antennae on a satellite) upon electronic command. Because of the damage of explosion in aerospace applications, and the weight of the satellite and other loads to be released, actuators must first restrain and then quickly release massive loads with a minimum mechanical shock imparted to the surrounding separate components or devices. Typically, such actuators utilize a multi-part spool held together by a wound restraining wire (with memory). A load is restrained by the barrier formed by the intersection of the parts of the spool (when held together by the restraining wire). A pin bears against the spool at one end of the pin and holds the load at the other end of the pin. A small frangible fuse keeps the restraining wire from unraveling until a weak electrical current causes the frangible fuse to fail in tension, to allow the restraining wire to unwind and thus to free and permit the parts of the spool to separate, eliminating the resistance to the load. Some actuators apply the full force of the load to the spool, while others utilize a series of moving parts to create a mechanical advantage, so that only a small portion of the load need be resisted by the spool. Typically, prior art devices used a single power supply.
The invention described in above-referenced patent application, Ser. No. 09/498,761, was designed to avoid problems exhibited in prior art devices.
As an improvement and variation of the invention described in above-referenced application Ser. No. 09/498,761, in its preferred embodiment, the present invention provides a redundant releasing mechanism, e.g., a fuse wire system, comprising at least two fusible links or fuse wires, which can be appropriately severed. The releasing mechanism is initiated by a power supply or fusible link/fuse wire decoupling device for the severable links. The power supply preferably is also redundant and typically includes at least two power supplies which may be individually coupled into the release mechanism fusible links as separate circuits where, should one power supply fail upon activation, the other will still initiate at least one of the fusible links. Typically, the releasing mechanism is coupled to a segmentable frangible actuator which is held together by a restraining wire wound about its segments. The restraining wire is coupled at one end to the release mechanism.
In responsive to current from the power supply, the release mechanism releases the restraining wire which, in turn, permits the segments of the frangible actuator to separate and thus release a load secured thereto.
More specifically, the release mechanism comprises two fusible links or fuse wires coupled to a load restraining agent or support which is embodied as an insulator hub. The fusible link couplings are so arranged that, upon breaking of either link, the insulator hub is freed from holding the frangible actuator as a unit and, thus, from restraining the load. Furthermore, each of the two fusible links may be paired to provide redundancy should any one of the fusible links prematurely break prior to a planned break of any fusible link and, therefore, to prevent premature decoupling of the restraining wire from the hub.
Several advantages are derived from this arrangement. The releasing actuation is rapid, and is assured by use of redundant circuitry. Additional confidence is provided by coupling the releasing mechanism to redundant power supplies to assure rupture of the fusible links, and by utilizing redundant fusible links to avoid premature releasing initiation before a desired or scheduled release.
Other aims and advantages, as well as a more complete understanding of the present invention, will appear from the following explanation of exemplary embodiments and the accompanying drawings thereof.